A map collection for time travelers

Few think to save roadmaps; we prize only current ones. Yet Berlo amassed an unexpected data jackpot. His maps, says Jon Christensen, an environmental historian at the University of California, Los Angeles, are snapshots of how America has viewed its past, present and future. On the cover of a 1973 map, for instance, Lady Liberty's lamp shines in concentric circles, clouds issue from Mississippi steamboats in lush, curling locks and Mount Rushmore's presidents are – I swear — sporting Afros. It's a psychedelic, utopian vision of America.

Berlo's map trove is being put to good use. Stanford political scientist Clayton Nall plans to study the maps to help link the rise of suburbs to increasing political polarization. And Christensen is using them for his CityNature project, which studies how Los Angeles and San Francisco set aside parks and open space. "As the population of the planet grows," Christensen says, "we know that means expanding the built urban environment. How that happens profoundly affects how well people live — with each other and nature. By comparing cities' (pasts) we can, I think, develop some guidelines to help shape city planning in the future." Christensen adds: "We think that in the age of Google all information lies beneath our fingertips. But historians still spend days doing archival work. These maps hold information that is not contained anywhere else."